I am trying to explore the implementation of Tuned Mass Damper Inerter (TMDI) in OpenFAST. For this purpose, I am carefully going through the theoretical background and equations of motion (EOMs) of TMD to develop an understanding of the necessary changes that are required in the EOMs so that a TMDI can be modelled.
In Equation 4.217, which computes the matrix A, the components angular velocity of nacelle are used. These are: phi^dot, psi^dot and Theta^dot. My understanding is that the subscript should be N/O_N rather than P/O_N. Or is it that Omega_N/O_n is same as Omega_P/O_n i.e, angular velocity the point to which TMD is attached has to be taken into consideration (whether it is nacelle, tower top or any other location)?
Best wishes,
Hisham
Dear @Hisham.Tariq,
I agree that appears to be a typo in the documentation and the subscript N/O_N should be used for these angular velocity terms, as they are used earlier in the documentation.
Have you seen other errors in the Structural Control (StC) theory documentation on readthedocs? I’ll plan to post an issue to get this fixed.
Best regards,
Dear @Jason.Jonkman,
Thank you for clarifying this issue. I found similar typo in the document “Theory Manual for the Tuned Mass Damper Module in FAST v8” by Cava and Lackner.
The focus of my review is “4.16.2. Theory Manual for the Tuned Mass Damper Module in OpenFAST“. While I am trying to rederive/reproduce the equation of motions and their state space representation, I did not pick up any other errors in this module of the documentation till now. I will post them here in case I suspect any errors.
Best wishes,
Hisham
Dear @Hisham.Tariq,
I believe the theory documentation of StC was based on the paper you cite, so, the typo was likely copied over.
I’ve now posted this issue in the OpenFAST GitHub repository: Bug report: Typo in Structural Control (StC) Theory Documentation · Issue #2992 · OpenFAST/openfast · GitHub.
Best regards,
Dear @Jason.Jonkman,
There may be one more correction. While computing forces and moments, it should be x_TMD_X/P_N and x^dot_TMD_X/P_N. Similarly, along y and z directions.
Best regards,
Hisham
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Thanks for posting! We’ll get these fixed soon.
Dear @Jason.Jonkman ,
A small typo above Eq. 4.215, It should be Fx and Fy (and not Fx and Fz).
Best wishes,
Hisham
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